Type 1 Diabetes and Exercise – The Highs, Lows and Management Strategies

By: Debora Sloan, BA, BSC, RD, CPT

Countless studies show that as little as 30 minutes of physical activity can make a difference to your health. More intensive exercise can elevate these benefits even further. Exercise benefits include: decreasing your risk for chronic disease, weight management, bone heath, mental health, and increased energy. But, how does this translate to those with Type 1 Diabetes?

It is important to distinguish Type 1 – insulin dependent diabetics – from those with Type 2 Diabetes, especially when discussing exercise. This article focuses specifically on Type 1. Management of the type 1 patient looks at daily fluctuations in glucose readings via finger prick testing, and continuous glucose monitoring (CGM sensors), paired with the Hemoglobin A1C, which indicates average control over a few months. While the benefits of exercise listed above hold true for someone with Type 1, including improved insulin sensitivity and carbohydrate tolerance, research to date DOES NOT correlate exercise with improved diabetes control. In fact, it may make it MORE challenging. Essentially, the unpredictable effects of different types, frequencies, and durations of exercise on hormones, insulin needs and metabolism across individuals, makes achieving optimal blood sugar control considerably more difficult.

Seeing clients in my practice and living with Type 1 for 22 years I can certainly speak to the challenges. As many Type 1 athletes experience, I too have struggled with lows mid workout, guzzling juice, despite efforts to stay lean. I have been told to increase carb intake based on a plethora of variable recommendations. I have had to tiresomely log blood sugars and make insulin adjustments based on what seem to be arbitrary and unpredictable parameters. And still, not always seeming to get it quite right.

So, if this is the case, how are we to advise Type 1 patients and athletes trying engage in daily exercise or achieve optimal sport performance? First, understanding the research on the topic of Type 1 diabetes and the effects of exercise is key. Here are some summary points.

  • Anaerobic, high intensity (HI) and resistance training are more likely to cause increases in blood sugar levels (hyperglycemia) during or in the immediate hours following the activity.
    This is due to the fight or flight adrenaline response without the self regulating insulin response. Elevated levels of these stress hormones trigger glucagon to release stored glucose (glycogen) from the liver into the bloodstream. Consider, in a non-diabetic this glucose release is adequately balanced by appropriate increases in insulin.
  • Low-Moderate intensity aerobic activities on the other hand, such as walking, jogging or cycling are associated with higher incidence of hypoglycemia during and in the hours following the exercise, including overnight. This is due to the high glucose uptake by the muscles without the counter-regulatory stress/glucagon response, accompanied by the inability to decrease circulating insulin. A non-diabetic self-regulates this process leading to euglycemia.
  • Competition stress or “race day” nerves can lead to unpredictable hyperglycaemia leading to poor performance and higher risk of ketoacidosis.
  • All types of exercise increase the risk of hypoglycaemia in the hours to days following the activity as exercise changes insulin sensitivity, glucose uptake by the muscles and overall metabolism.
  • Management is highly individual, however studies show the application of CGM and insulin pump therapy provide improved confidence, pattern recognition, and control for the diabetic athlete.
  • Fuelling for sport performance as a Type 1 athlete follows the same principles as those for the non-diabetic athlete. The goal when possible is to to fuel as an athlete first and a diabetic second. However, good glucose control and understanding individual response to various exercise regimens is paramount for this to happen.
  • The study of Type 1 and exercise is challenging. Research is often limited by small control groups, and controlling for glucose fluctuations during study. It is also stronger for steady state regimens as they are easier to study in the lab. More research is needed, especially for higher intensity, ‘mixed’ sports.

In summary, finding the perfect balance for an active type 1 or high performing athlete presents a plethora of challenges and warranted frustrations. It also takes a large commitment by the athlete, their coach, and their health team. Both high and low blood sugars are possible and require strategic treatment pre, during and post exercise. Fluctuating and unpredictable glucose levels can cause disruption to performance and may present safety concerns. This is often confounded by the treatment of and rebounding effects from hypoglycemia and hyperglycemia which can precipitate continued patterns of highs and lows affecting performance, body composition and overall blood glucose control.

Moving away from the negatives, competitive performance and optimal blood sugar control is possible and is being achieved by many athletes globally, including Canadian rower Chris Jarvis
and hockey star Max Domi! Research is ongoing and technological advancements including faster acting insulin formulations, insulin pump therapy, and glucose sensors are on the market. These sensors AKA continuous glucose monitoring (CGM), provide Type 1’s the ability to see and react to trends in real time with regards to glucose patterns and insulin dosing. Many of these are compatible with iPhone and Android APPs. The technology’s alerting capability helps prevent severe hypo and hyperglycemia leading to improved athlete confidence when training.

Bottom line, regardless of the activity of choice, being armed with an in-depth understanding of both the science and the individual response to foods, blood glucose patterns, and various exercise regimens will allow for optimal management and performance. When it comes to the co-existence of diabetes and the athlete in sport and performance the goal is to fuel as an athlete first and the more knowledge we have the more able we can be an athlete first.

My key tips for management, as a practitioner and active Type 1 myself, would be:

Avoid over-treating exercise induced lows and over-correcting for highs. Making smaller, more controlled adjustments, using controlled amounts of glucose so you can track your response
helps avoid rebounding which allows for better control.

Utilize CGM technology and pump therapy as a way to better understand patterns and more accurately dose insulin around activity. From here, fuelling as an athlete first becomes much more possible.

If you are or are working with an active Type 1, finding a supportive diabetes nurse educator, dietitian and endocrinologist versed in the area of exercise to help is key. Other helpful
resources include:

  • Getting Pumped, Mike Riddell’s new publication highlighting new research in the area, case studies on athletes and practical tips for exercising with Type 1.
  • Pumping Insulin, which will provide the tools to self manage dosing and carb intake

Are you an athlete or a coach needing more customized guidance in the area of exercise and Type 1 diabetes? Contact Debora Sloan, RD. www.deborasloanhealthysolutions.com